Winter visitors: the Monarch Butterfly Migration reaches California

It’s a special time of year along the California coast, eagerly anticipated year after year: the return of the monarch butterflies.

Frequent Flyers
Beginning in October and peaking in December, the butterflies will remain in California until late winter, when they embark on their return trek to Mexico. One of the most popular locations to see them is in Pacific Grove, near Monterey. They are attracted to the area’s lush eucalyptus groves, where the monarchs nest. 

The creatures are also attracted to milkweed, their primary source of food. Because it is also a common allergen, milkweed is often removed from private gardens and public parks across the country, and that affects the butterfly populations.

Their numbers are declining, and fast: according to a recent study published in Biological Conservation, their numbers have plummeted from 10 million to around 300,000 since the early 1980s. 

Dr. Karen Oberhauser, professor of Fisheries, Wildlife, and Conservation Biology at the University of Minnesota (photo courtesy of Karen Oberhauser)

Vulnerable Beauties
Karen Oberhauser is professor of Fisheries, Wildlife, and Conservation Biology at the University of Minnesota and has studied the travel and habitats of these winged wonders extensively. According to NBC News, Oberhauser reports a decline in the monarch population of ninety percent since 1995.

Oberhauser and others believes that changes to the areas where the monarchs stop during their migration are behind the decline of the species.

“Because the monarchs are concentrated in a very small area in the winter, they are more vulnerable during this stage of their life,” Oberhauser told NBC News. “However, breeding sites in Canada and the US are also crucial to their survival, and additional losses of these sites also pose threats. There are no laws in the US to protect their habitat.”

Researches and conservation groups are strengthening their efforts to save the butterflies before it’s too late.

A monarch butterfly photographed by C. P. Ewing

Eric Sachs is a Science and Policy Lead at agricultural chemical company Monsanto, whose pesticides are often blamed for the decline of a primary monarch feeding ground: the wild milkweed found on farms across the country.

“We agree with the experts that have identified a number of factors that contribute to the decline in monarch population. We also agree that the place to focus our efforts is on restoring habitat outside farm fields,” he told NBC News. Monsanto also claims it is evaluating options for replenishing milkweed and is working with farmers and conservation groups to reach a solution.

Where to find them
The California coast is home to several sites where monarchs nest during their migration, from the North Bay to San Diego. Check out the map below to find the best places to see the orange and black insects.

Related stories:
Slideshow: Monarch butterfly stages of development
Top 5 Places to See California’s Wildlife


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